Access door for liquid containers



Dec. 21, 1948, F. J. PEPERSACK 2,457,056

ACCESS DOOR FOR LIQUID CONTAINERS 'FiledAug. 25, 1943 FIGURE I FIGURE 2FIGURE. 4-

FIGURE 3 INVENTOR.

FRANCIS .J FEFERSACK A TORNEY Patented Dec. 2 1, 1948 ACCESS DOOR FOR.LIQUID CONTAINERS Francis J. Pepersack, Towson, Md., assignor to TheGlenn L. Martin Company, Middle River, Md., a corporation of MarylandApplication August 25, 1943, Serial No. 499,897

Claims. (01. 150-3) This invention relates generally to liquid holdingtanks and is particularly concerned with tanks having flexible walls andliquid-tight seals around access doors in such walls.

In certain industries tanks of special construction are required,particularly when they are to hold certain liquids. For example,airplane fuel tanks have been made with laminated, flexible walls asdescribed in U. S. Patents Nos. 2,102,590 and 2,321,417. Since suchtanks must be provided with one or more openings to permit access to theinterior thereof for various purposes, including the connecting ofoutlet fittings to the tank, and since it is essential that there shouldbe no leakage of liquid about the access door, various efforts have beenmade to provide access door constructions which would be suitable andsatisfactory.

Heretofore tanks of the class described have had access doors secured tothe outer side of the tank as by bolts extending through the door andengaging the threads of nuts embedded in the tankwall around the accessopening. This construction has not been entirely satisfactory for thethreads in the nuts often become stripped, thus making it diflicult, orimpossible, to press the cover closely enough against the outer surfaceof the tank to prevent escape of liquid through the access opening,especially when that opening is at the bottom or on, the side of a largetank. The entire tank becomes useless and has to be discarded when thenuts, or a suflicient number of them, are stripped to the extent thatleakage of liquid is permitted.

The present invention aims to avoid the disadvantages of priorconstructions and achieves this aim by making a sealing-connectionbetween the outer surface of the door and the inner surface of the tankand by embedding nuts in the cover rather than in the tank, thuspreventing the installation of the door or cover with the wrong side ofthe same being placed in contact with the liquid, which would rapidlydeteriorate the material comprising the outer portion of the door. Theweight of the liquid contents of the tank and pressures existing in thetank assist in preventing leakage, and if any nut should become strippedor loose on the spline in the door only the door need be discarded.Accordingly, the present invention is an important improvement over theprior art in various respects, in-

cluding economies and results.

In the drawings accompanying and forming a part of this specification,

. canized rubber.

Figure 1 is a perspective view of a tank embodying the presentinvention;

Figure 2 is a plan view of the access door of the tank of Figure 1;

Figure 3 is a fragmentary, sectional view of parts of the tank andaccess door taken'on line 3-3 of Figure 1;

Figure 4 is a side .elevational view of the door of Figure 2; and

Figure 5 is a fragmentary, perspective view of the perforated ring andnuts embedded in the door of Figures 1 to 4.

, The tank I of Figure 1 may be of any desired size or shape and isprovided with any desired number of outlet openings 2 and with an accessopening closed by door 3.

The walls of tank i may be composed of any suitable'flexible materialand may, if desired, be laminated after the manner described in theabove mentioned patents. When the tank is to be used for gasoline on anairplane, the tank walls (see Fig. 3) may consist of an inner layer 4 ofmaterial resistant to gasoline, such for example as the synthetic rubbercommercially known as neoprene, an intermediate layer 5 of crude,unvulcanized rubber, and an outer layer 8 of vul- It will be understoodthat the walls of tank I may be composed of various other suitablematerials, depending on the liquids the tank is to contain and theservice conditions under which the tank is to be used.

The outlets 2 are provided with suitable outlet fittings and for thispurpose the fittings of Patent No. 2,321,417 may be employed. Theattachmentv of those and similar fittings to the tank walls may requireaccess to the interior of the tank which is afforded by the openingwhich, in Figure 1, is covered by door 3. Such openings permitinspection and repair of the entire tank interior.

In Figures 2 to 5 one embodiment of the present invention is shown. Inthese figures the flexible wall of the tank consists of the laminations4, 5 and 6 above described. This wall is provided with an opening,preferably oval or rectangular in shape. A door frame I, composed of anysuitable material such as synthetic rubber, is fitted in the openingthrough the tank wall and, as better shown in Figure 3, comprises aflexible member bifurcated along its outer periphery to form flanges 8and 9 which engage, and are secured with liquid sealing contact to, theouter and inner surfaces of the tank wall, respectively. This frame. 1,near its inner edge, has

embedded therein a perforated annulus II and as synthetic rubber.

thus constitutes a rigid-ring assembly. Holes are formed in the materialof frame I in alignment with the perforations in annulus ll so thatbolts ll may extend through the frame 'i and annulus l0.

The access door I is preferably composed of a central portion or panelI? which is flexible and is composed of laminations like those of thewall I, that is laminatlons 4, [and I 'above described. The door 3includes a peripheral portion M which may be composed of any suitablematerial such This peripheral portion is preferably a separate memberwhich is bifurcated along its inner edge to form flanges l5- and I8which engage. and are secured to. the outer and inner surfaces of panelI! with liquid-sealing contact. A perforated ring I1 is embedded in theperipheral portion I! of the door near itsouter periphery. This ring ll,as well as annulus I0. is composed of a relatively stiff, nondeformablematerial, .such as metal, molded Bakelite or the like. Nuts i8 providedwith shoulders I8 and longitudinal serrations 2B are disposed inperforations 2| of ring I1 in such a manner that the nuts i8 may notrotate relative to the ring IT. The shoulders i9 press against onesurface of the ring I! and prevent'fmovement of the nuts axially towardannulus l0 and relative to the ring;

It will be noted from Figure 3 that the peripheral portion M of accessdoor I is offset with respect to the panel I: so that when the door isassembled with theitank the outer surface of peripheral portion, M willengage the'inner-surface of door frame 1, and that when the door andtank are so assembled the perforations in rings ill and i1 may bealigned. when aligned, the bolts II which project into the tank throughannulus Ill may be thijeaded into the nuts I! of the door. since theaccess opening is'oval in shape, the door 3 may be passed therethroughand then turned into the position shown in Figures 1 and 3, whereuponboltsiil may be inserted through the holes in the frame and screwed intothe nuts i8, thereby bringing the outer surface of the peripheralportion of-the door into liquid sealing engagement with the: innersurface of the door frame. f

It will be understood that when the door 3 is in the bottom or sidewalls of a tank containin liquid the weight of the liquid on the doorwill tend to increase the sealing contact of the door on the tank wallsor door frame and thus such weight will tend to decrease theliability'of leakage of liquid past the door; Similarly,"any" pressureexisting in the tank will pressthe door against the tank wall andincrease the liquid-sealing contact therebetween.

If and when any nut is has stripped threads or loses its non-rotationalcontact with ring 'i'l, the door may be replaced without any changebeing made in the tank or door frame.

While a preferred embodiment of the present invention has been describedher-inabo've, it will be understood that many changes may be madetherein without departing from the present invention. For example-thoheaded bolts-ii may be replaced by studs'detachably or permanently fixedto nuts it or their equivalents, and nuts may replace the heads of boltsll. Also, the door frame I may be an integral part of the wall of thetank: and the peripheral portion ll -oi! the door may be integralwithpanel i2.

Furthermore, the D-rings 2! or the door, as

shown in Figure 2, may be replaced by any quivalent handle or desiredgripping means which will enable one to hold the door while it is beinglocated in the desired position within the tank. Furthermore, the nutsI. may be replaced by threads formed in perforations 2| of ring il, if

desired. Other variations of the construction hereinabove shown anddescribed, and not amounting to invention in themselves, may be madewithin the scope of the present invention.

Having thus described the invention so that others skilled in the artmay be able to understand and practice the same. I state that what Idesire to secure by Letters Patent is defined in what is claimed.

What is claimed is:

1. In a tank for liquids, a wall consisting solely of flexible.rubber-like material. having an access opening. a perforated rigid ringassembly secured to the tank in liquid sealing relation to said opening.a door of similar flexible material for said opening having a peripheralportion provided with an outer surface to engage the inner surface ofthe rigid ring assembly about the said opening, a perforated rigid ringembedded in said peripheral portion of said door, and means includingscrew-threaded members disposed in aligned perforations of said ring andsaid ring assembly for pressing the said inner and outer surfacestogether with liquid-sealing contact.

2. In, a tank for liquids, a flexible wall of rubber-like materialhaving an access opening, a

perforated rigid annulus embedded in said wall a around said opening, adoor of similar rubberlike material for saidopening having a flexibleperipheral portion to engage the inner surface of said flexible wall, aperforated rigid ring. interiorly threaded nuts nonrotatably mounted insaid perforations, said ringand nuts being embedded in said peripheralportion of the door, and means including screw-threaded membersextending thru the perforations of said annulus and engaging threads insaid nuts for clamping the outer surface of the peripheral portion ofthe'door against the inner side of the flexible tank wall withliquid-sealing contact.

3. In a tank for liquids, a wall of flexible, rubber-like materialhaving an opening therethru, a door frame of similar material secured tosaid wall in said opening by a liquid-tight seal, a perforated rigidannulus embedded in said frame, a door of rubber-like material for saidframe, said door comprising'a panel and a peripheral portion havingflanges engaging and secured to the outer and inner surfaces of saidpanel in liquid-tight relation to each other, a perforated rigid ringembedded in said door near its periphery, and means including threadedmembers extending thru the annulus in said frame and into the ring forforming a liquid tight seal between the outer surface of the door andthe inner surface of said frame.

4. In a tank for liquids, a wall of flexible, rubber-like materialhaving an opening therethru; a door frame of similar material in saidopening and having flanges at its outer periphery engaging and securedto the inner and outer surfaces of the tank wall by a liquid-tight seal,a

perforated rigid annulus embedded in said frame.

5 through the annulus in said frame and into the ring for forming aliquid-tight seal between the outer surface of the door and the innersurface of having a peripheral portion provided with an 19 3,326,263

outer surface to engage the inner surface of the rigid ring assemblyabout the said 0, e perforated rigid ring embedded in said peripheralportion of said door, endmeans including screwthreaded members disposedin aligned perforetions of said ring and said. ring assembly forpressing the said inner and outer surfaces to gether with liquid-sealingcontact.

FRANCIS J. FEPKRBAGK.

' I Number summons crrsn tile of this patent:

' UNITED s'm'rzs PATENTS Name v Date 1,406,478 'Mote Feb. 14, 19221,480,782 Primeau Jan. 15, 1924 Steiner Aug.- 10, 1942 2,336,885Pepersack Dec. 14, 1943 2,376,799 Kelley Mar. 6, 1945 I FORHGH PA aNumber Country Date 1 443,379 Great Britain Mar. 11, 1936 $6,565 GreatBritain Dec. 1, 1938

